Physical Sciences Inc., with our clinical partners in the Dept of Oral and Maxillofacial Surgery at the Massachusetts General Hospital, propose to develop a marking system for navigation during orthognathic surgery. The device can be used for both endoscopic and open procedures. It can be used to transfer treatment plans from computer-based 3D surgical planning tools or cephalometric tracings onto the bone. The system will provide for intraoperative registration of the image to the patient, with no requirement for fiducial markers in the pre-operative images and no fixation frame attached to the head. Examples of procedures where OsteoMark might be used include minimally-invasive (endoscopic) reconstruction and distraction osteogenesis. Once the marks are made, the surgeon will complete the procedure using instruments without any tracking, using the marks to guide the modification of bone. The proposed device will be less expensive and less complex than a system that tracks the motion of multiple surgical instruments as procedures are performed. We are proposing to develop navigation based on both 2D and 3D pre-operative images, though Phase I will address only the 3D images. OsteoMark will be developed to interact with the open-source medical imaging software Slicer/Osteoplan. In Phase I, we will fabricate the prototype marker, develop a rudimentary software interface for Slicer, and characterize its performance in a series of bench tests. The capstone feasibility demonstration will be a set of endoscopic procedures performed in porcine cadaver heads, from which we will quantify the performance of the marking device in an environment that closely resembles an operating-room. Public Health Significance: Minimally-invasive surgery is becoming more widely used in reconstruction of bones in the face because it results in faster recovery times, less pain and discomfort, and less scarring than open procedures. Another recent advancement has been the use of computer graphics tools to plan complex reconstruction operations. We are proposing to develop a device that will enable surgeons to copy computer treatment plans to the bone even through a very small incision, allowing surgeons to perform more sophisticated procedures with less difficulty for the patient. [unreadable] [unreadable] [unreadable]